1. Field of the Invention
The present invention relates generally to the field of sensing probes used in relation to chemical processing systems and more specifically, to systems for arranging and maintaining sensing probes in position to effectively perform their sensing functions in regard to chemical reactor vessels and containers used in the chemical processing field.
2. Background of the Prior Art
The processing of fluids, as is generally practiced in the chemical industry, usually requires the measurement of a variety of properties in chemical products during the various stages of their production. Such measurements are used to determine the precise nature of process conditions respectively at discreet points during the various phases through which materials pass, from the beginning of a chemical processing system to the end. The term chemical processing is used in the broadest sense to include the production of food products as well as the production of liquids and gases.
A significant portion of the field of chemical processing includes the use of enclosed reactor vessels of a variety of types, styles, and designs in which the discreet steps of the various processes to be performed, are accomplished. Within these reactor vessels, a variety of conditions are imposed on the chemicals passing therethrough which tend to cause or promote chemical, physical and/or electrical reactions which relate to steps in the processing of those chemicals. Many of the reactions which are caused or promoted within such reaction vessels tend to cause or promote corrosive reactions with the reactor vessels which contain them. Thus, sensing probes which are used in connection with such reactor vessels, or the flow lines associated with them, are required to be resistant to the corrosion. Needless to say, the vessels themselves, as well as their flow lines, also need to be resistant to such corrosion.
One highly successful approach to corrosion resistance in such reactor vessels, and within their associated flow lines, is to coat the surfaces within those vessels and flow lines, which are in contact with the corrosion produced by the chemical reactions, with glass. Another successful approach is to line the interiors of such reaction vessels and their associated flow lines with thin coatings of extreme corrosion resistant metals such as tantalum or titanium. Chemical reaction vessels of both types are produced by The Pfaudler Co. of Rochester, New York, and marketed respectively under the trademarks "Glasteel" and "Resista-Clad".
In addition to being corrosion resistant many chemical reactor vessels are required to operate for extended periods of time under conditions of pressure differentials of varying degrees, including both internal pressurization and vacuums. Also, such reactor vessels, in many cases, are required to operated at substantially elevated temperatures.
A variety of different sensing probes are readily available on the market. Many of these are adapted for corrosion resistant service and also for service where significant pressure and temperature differentials exist. For example, a glass coated pH sensing probe is disclosed in U.S. Pat. No. 3,787,307 and is presently marketed by The Pfaudler Co. of Rochester, N.Y., and the Pfaudler-Werke AG of Schwetzingen, Germany. A variety of other corrosion resistant sensors for sensing temperature, hydrogen ion concentration, corrosion resistant coating defects, localized pressures, etc. are likewise readily available in the marketplace. Usually these probes take the general physical shape of a long thin cylindrical body.
Many of the chemical reactor vessels that are used in the chemical processing industry tend to be rather large, exceeding several hundred gallons and upwards in size. Of these large vessels, many are stand-alone in that they are not attached to other items of machinery or equipment. Because of the nature of the processes to which such chemical reactor vessels are applied, in many cases the vessels need to be inside of a building. In respect to such buildings the chemical reactor vessels tend to be relatively large in relation to the building space alotted to them. Specifically, they tend to reach from the floor to the ceiling, being longer in length than in diameter size to save floor space. In addition, because of general requirements for gravity flow from the flow lines into the reactor vessels, in many cases there is an agglomoration of piping above the reactor vessels. The result of such arrangements is that there is little overhead room. That is, the distance between the uppermost part of the chemical reaction vessel in many situations tends to be very close to the roof or ceiling line of the interior of the building or very close to the overhead piping.
To be effective, the probes need to be rather long in length, extending through the uppermost portions of a chemical reactor vessel and extending through the interior of that same vessel to near its bottom or floor. The reason for this is that there is a need to sense various phenomena in the chemical fluids both when the vessel is full and when the vessel is nearly empty. The reason for inserting the probes through the top of the reactor vessel as well as other ports into the vessel which are subject to being opened from time to time, is to inhibit the occurance of spills and leaks of chemicals from the vessel itself.
Such sensing probes for use in relatively tall chemical reactors, because of the proximity of the roof line and/or pipe lines above the reactor vessel, are normally serviced and/or changed by shutting down the chemical process, evacuating the vessel and removing port covers from the vessel through which a man enters the vessel. This is a very difficult and time consuming procedure. In addition, it is quite dangerous to the individual who is required to perform the task. It is also an economically detrimental procedure because it requires that the chemical processing line, or at least that portion of it which uses that particular reactor vessel, must be shut down and taken out of service. Sensing probes need to be serviced and/or replaced, from time to time, to eliminate chemical product build-up on the sensor probe and to recalibrate the sensing elements to ensure accurate read-outs and monitoring capability, as well as correction of breakage and other service failures.
Thus there is a need for a system by which sensing probes can be detached from and withdrawn from the interior of reactor vessels without having to evacuate the vessel where liquids are being processed and without a man actually having to enter the vessel. Since most sensing probes are arranged vertically within reaction vessels, necessitating their introduction through the jacket of the vessel at or near the very uppermost portions of that vessel, there is a need for a system whereby a sensor probe can be introduced through an aperture in the top of the vessel such that it can be extended all the way to near the bottom or floor of the vessel in a low headroom situation.